How to use UIAlertController to replace UIActionSh

问题:

I am maintaining an old iOS project which based on SDK 6.0.

A method on this project called

-(void) showComboBox:(UIView*)view:withOptions:(NSDictionary*)options

is used to show a combo box. To achieve the goal, it used UIActionSheet, which is deprecated on iOS8.

My solution is like this:

        if (floor(NSFoundationVersionNumber) > NSFoundationVersionNumber10_8) {
        UIAlertController* alertController = [UIAlertController 
           alertControllerWithTitle:@"title" 
           message:@"message" 
           preferredStyle:UIAlertControllerStyleActionSheet];

        UIAlertAction* item = [UIAlertAction actionWithTitle:@"item" 
           style:UIAlertActionStyleDefault 
           handler:^(UIAlertAction *action) {
            //do something here 
            //inform the selection to the WebView 
            ...
            [alertController dismissViewControllerAnimated:YES completion:nil];
        }];

        UIAlertAction* cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
            [alertController dismissViewControllerAnimated:YES completion:nil];
        }];

        [alertController addAction:item];
        [alertController addAction:cancelAction];
        //I am not sure whether it's the right way
        if ([view.nextResponder isKindOfClass:UIViewController.class]) {
            UIViewController* vc = (UIViewController*)view.nextResponder;
            [vc presentViewController:alertController animated:YES completion:nil];
        }

Is that a proper solution?

This is what I mostly concern about: UIAlertController needs to be added to a UIViewController but I can only get the pointer of the UIView, so I used view.nextResponder to get what I want, but it's that a good way?

回答1:

I have used following code to show action sheet using UIAlertViewController and it works perfect.

- (IBAction)buttonClicked:(id)sender {

    UIAlertController *actionSheet = [UIAlertController alertControllerWithTitle:@"Action Sheet" message:@"Using the alert controller" preferredStyle:UIAlertControllerStyleActionSheet];

    [actionSheet addAction:[UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {

        // Cancel button tappped.
        [self dismissViewControllerAnimated:YES completion:^{
        }];
    }]];

    [actionSheet addAction:[UIAlertAction actionWithTitle:@"Delete" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {

        // Distructive button tapped.
        [self dismissViewControllerAnimated:YES completion:^{
        }];
    }]];

    [actionSheet addAction:[UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {

        // OK button tapped.

        [self dismissViewControllerAnimated:YES completion:^{
        }];
    }]];

    // Present action sheet.
    [self presentViewController:actionSheet animated:YES completion:nil];
}

Edit:

You need to get UIViewController object here. You can set global variable or call a delegate method, or you can use notification to get view controller object in this code.

and last line in above code will be like.

[self.viewController presentViewController:actionSheet animated:YES completion:nil];

self.viewController is a global variable which will be set before you actually get this view.

Because the approach you are following now using view.nextResponder. I'm afraid that it may not work.

回答2:

I have used action sheet for changing profile picture. I followed Kampai approach, just removed dismissviewController call since it was kicking me out of a view when pressing Cancel or photo selection view

UIAlertController *actionSheet = [UIAlertController alertControllerWithTitle:nil message:nil preferredStyle:UIAlertControllerStyleActionSheet];

[actionSheet addAction:[UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {

    // Cancel button tappped do nothing.

}]];

[actionSheet addAction:[UIAlertAction actionWithTitle:@"Take photo" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {

    // take photo button tapped.
    [self takePhoto];

}]];

[actionSheet addAction:[UIAlertAction actionWithTitle:@"Choose photo" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {

    // choose photo button tapped.
    [self choosePhoto];

}]];

[actionSheet addAction:[UIAlertAction actionWithTitle:@"Delete Photo" style:UIAlertActionStyleDestructive handler:^(UIAlertAction *action) {

    // Distructive button tapped.
    [self deletePhoto];

}]];

回答3:

Swift update -

    let actionSheet = UIAlertController.init(title: "Please choose a source type", message: nil, preferredStyle: .actionSheet)
    actionSheet.addAction(UIAlertAction.init(title: "Take Photo", style: UIAlertActionStyle.default, handler: { (action) in
        self.openCamera()
    }))
    actionSheet.addAction(UIAlertAction.init(title: "Choose Photo", style: UIAlertActionStyle.default, handler: { (action) in
        self.showPhotoLibrary()
    }))
    actionSheet.addAction(UIAlertAction.init(title: "Cancel", style: UIAlertActionStyle.cancel, handler: { (action) in
        // self.dismissViewControllerAnimated(true, completion: nil) is not needed, this is handled automatically,
         //Plus whatever method you define here, gets called,
        //If you tap outside the UIAlertController action buttons area, then also this handler gets called.
    }))
    //Present the controller
    self.present(actionSheet, animated: true, completion: nil)

回答4:

Swift 4

        let alert = UIAlertController(title: "Select One", message: nil, preferredStyle: UIAlertControllerStyle.actionSheet)
        alert.addAction(UIAlertAction(title: "Cancel", style: UIAlertActionStyle.cancel, handler: nil))
        alert.addAction(UIAlertAction(title: "Export", style: UIAlertActionStyle.default, handler: { (action) in

            // TODO: Export wordlist

        }))
        alert.addAction(UIAlertAction(title: "Import", style: UIAlertActionStyle.default, handler: { (action) in

            // TODO: Import wordlist
        }))

        self.present(alert, animated: true, completion: nil)

回答5:

You can use view.window.rootViewController instead. If you don't care about presenter it is fine.

回答6:

While it may look very simple, there is a nasty issue with using UIAlertController. It is memory leaks prone. In order to test if you have the issue, just put a breakpoint at your view controller's dealloc method and see if it's deallocated properly.

I was looking for a solution for quite some time and here is how I use an alert controller in my app.

+ (void)alertWithPresenting:(UIViewController *)presenting title:(NSString *)title
                       text:(NSString *)text buttons:(NSArray *)buttons
                    handler:(void (^)(UIAlertAction *action, NSUInteger index))handler
{
        UIAlertController *alert = [UIAlertController
                                    alertControllerWithTitle:title message:text
                                    preferredStyle:UIAlertControllerStyleAlert];
        __weak __typeof(alert) weakAlert = alert;
        for (NSString *title in buttons) {
                UIAlertActionStyle style = UIAlertActionStyleDefault;
                if ([title isEqualToString:[L10n cancelButton]])
                        style = UIAlertActionStyleCancel;
                else if ([title isEqualToString:[L10n deleteButton]])
                        style = UIAlertActionStyleDestructive;
                else if ([title isEqualToString:[L10n archiveButton]])
                        style = UIAlertActionStyleDestructive;

                UIAlertAction *action = [UIAlertAction actionWithTitle:title style:style handler:^(UIAlertAction *action) {
                        if (handler != nil)
                                handler(action, [buttons indexOfObject:action.title]);
                        [weakAlert dismissViewControllerAnimated:YES completion:nil];
                }];
                [alert addAction:action];
        }
        [presenting presentViewController:alert animated:YES completion:nil];
}

This is not all. Here is an example of how you use it in your view controller. In my case its tableview with search, so presenting controller may be different.

- (void) deleteCases:(NSArray *)selectedRows
{
        NSString *text = NSLocalizedStringWithDefaultValue(@"cases.delete.alert.text",
                                                           @"Localizable",  [NSBundle mainBundle],
                                                           @"Deleted cases cannot be restored. Continue with delete?",
                                                           @"Delete alert text");
        NSString *title = NSLocalizedStringWithDefaultValue(@"cases.delete.alert.title",
                                                            @"Localizable",  [NSBundle mainBundle],
                                                            @"Delete cases", @"Detete alert title");
        UIViewController *presenting = self.searchController.active ? self.searchController : self;
        __weak __typeof(presenting) weakPresenting = presenting;
        __weak __typeof(self) weakSelf = self;
        [YourClassName alertWithPresenting:weakPresenting title:title text:text
                                   buttons:@[[L10n deleteButton], [L10n cancelButton]]
                                   handler:^(UIAlertAction *action, NSUInteger index)
        {
                if (action.style == UIAlertActionStyleDestructive) {
                        __typeof(weakSelf) strongSelf = weakSelf;
                        // Perform your actions using @strongSelf
                }
         }];
}